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<div class="moz-cite-prefix">Theory offers another possible solution
to the puzzle that brains can function in a stable manner,
although neural codes drift, as demonstrated most recently through
experimental data in the Neuron paper by Driscoll et al. from the
Harvey Lab. The preprint<br>
<br>
Reward-based stochastic self-configuration of neural circuits<br>
<br>
<a class="moz-txt-link-freetext" href="https://arxiv.org/abs/1704.04238">https://arxiv.org/abs/1704.04238</a><br>
<br>
shows that from a theoretical perspective stable reward-based
learning does not require stable neural codes or stable synaptic
connections. In fact, it is likely to work better without them.<br>
<br>
<pre class="moz-signature" cols="72">--
David Kappel
Institute for Theoretical Computer Science
Graz University of Technology
Inffeldgasse 16b, A-8010 Graz, Austria
Tel.: ++43/316/873-5847
<a class="moz-txt-link-freetext" href="http://www.igi.tugraz.at/kappel/">http://www.igi.tugraz.at/kappel/</a></pre>
<br>
On 2017-08-27 05:54, Richard Loosemore wrote:<br>
</div>
<blockquote type="cite"
cite="mid:7f062bdd-0117-13f0-0ebf-d502be0ab778@susaro.com">
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<br>
Back in 2010 I wrote a paper with T.A. Harley in which we argued
that "concepts" (like [grandmother]) are likely to be <b>virtual</b>
patterns of activity on neural circuits and NOT hard coded into
the circuits themselves.<br>
<br>
So, for example, a virtual pattern of activity might come and go
between active and dormant states, or it could move around the
brain (perhaps from one column to another).<br>
<br>
In support of this conclusion, we pointed out that common
interpretations of brain imaging data were simply not consistent
with the usual assumption, which is that neurons directly
represented concepts. We pointed, in particular, to the infamous
Jennifer Aniston Cell paper, where the virtual concept hypothesis
was the only viable one.<br>
<br>
And yet, the "virtual" idea is almost completely absent from the
literature. Why? If concepts are virtual, this would make a
nonsense of many interpretations of neuroscience results, because
firing patterns would only have a weak relationship to meaningful
entities like concepts. (Think about it: if concepts can wander
around the cortex, what is the point in saying that a particular
place in cortex corresponds to a semantically tangible thing?).<br>
<br>
Anyway, I note that a recent paper from Laura N. Driscoll, Noah L.
Pettit, Matthias Minderer, Selmaan N. Chettih, and Christopher D.
Harvey (Dynamic Reorganization of Neuronal Activity Patterns in
Parietal Cortex):
<title>Dynamic Reorganization of Neuronal Activity Patterns in
Parietal Cortex</title>
<br>
<br>
<a class="moz-txt-link-freetext"
href="http://www.cell.com/cell/pdf/S0092-8674%2817%2930828-0.pdf"
moz-do-not-send="true">http://www.cell.com/cell/pdf/S0092-8674(17)30828-0.pdf</a><br>
<br>
(Overview here:
<a class="moz-txt-link-freetext"
href="http://news.harvard.edu/gazette/story/2017/08/brain-flexibility-changes-the-way-we-remember-and-learn/"
moz-do-not-send="true">http://news.harvard.edu/gazette/story/2017/08/brain-flexibility-changes-the-way-we-remember-and-learn/</a>)<br>
<br>
... brings yet another confirmation of the "virtual" concept
hypothesis. The most parsimonious interpretation of their results
is that the activity patterns are changing precisely because the
"concepts" (when active) are not identifable with fixed hardware,
but are actually virtual.<br>
<br>
It seems to me this is one of the most important issues in all of
neuroscience, since it changes the flavour of every result out
there.<br>
<br>
What do you think?<br>
<br>
---<br>
<br>
Richard Loosemore<br>
<br>
<br>
<br>
Reference<br>
<br>
Loosemore, R.P.W. & Harley, T.A. (2010). Brains and Minds: On
the Usefulness of Localization Data to Cognitive Psychology. In M.
Bunzl & S.J. Hanson (Eds.), Foundational Issues in Human Brain
Mapping.Cambridge, MA: MIT Press<br>
<br>
<a class="moz-txt-link-freetext"
href="https://www.academia.edu/563588/Brains_and_Minds_On_the_Usefulness_of_Localization_Data_to_Cognitive_Psychology"
moz-do-not-send="true">https://www.academia.edu/563588/Brains_and_Minds_On_the_Usefulness_of_Localization_Data_to_Cognitive_Psychology</a><br>
<br>
</blockquote>
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